The objective of this project is to develop a dedicated clinical system for testing and analyzing ocular motility. Commercially, our goal is to produce a low-cost, user-friendly hardware/software package specifically designed to allow clinical personnel with no computer training to quantitatively analyze (on-line) the eye movements produced in patients during pursuit tracking, random saccade tests, caloric irrigation, optokinetic and positional nystagmus testing and (optionally) rotatory tests of vestibular function. A central control/analysis unit will be developed utilizing the latest microprocessor and memory technology, programmed using proven software algorithms. A solid-state stimulator for smooth-pursuit and optokinetic testing will be developed as well as a solid-state thermal probe for caloric stimulation. Phase I is dedicated to investigating a new means of monitoring eye movements using phase-sensitive detection of a high-frequency carrier signal impressed across the eye to measure impedance changes produced by eye movements. Lock-in amplifier and phase-locked loop technologies will be utilized to detect and process the phase-shift information. The success of this project would provide a new atraumatic means for monitoring eye movements which overcomes several major problems inherent in conventional EOG recordings.